1. Field of Invention
The present invention relates to an electrode structure of a lithium battery, and more particularly to formation of a conductive electrode structure of the lithium battery by wrapping instead of direct penetrating, thus achieving a hermetic effect of conductive positions of the electrode.
2. Related Art
The lithium battery can be taken as a power supply for high quantity of electricity demands due to significant breakthrough of the material technology (for example, lithium iron phosphate rechargeable battery), for example, to be used in devices with high electricity demands such as electric bicycles and electric wheelchairs, and both storage capacity and power supply of such a non-aqueous electrolytic solution secondary battery with high capacity are greater than those of the traditional lithium battery. The secondary lithium battery and its battery tank are usually aluminum metal tanks. Generally, a metal tank is made by aluminum or stainless steel into a cylindrical shape or a square shape with at least one end having an opening. After a positive pole, a negative pole, and an isolating film of a battery are packaged in the metal tank, to maintain a long-term stable hermeticity in the battery, opening positions of the battery tank may be indeed closed with a lid body through different hermetic technologies, so as to ensure that the battery has good waterproof and gas-tight performances.
An electrode of the existing square lithium battery configures an electrode terminal electrically connected to the external on the lid body, an insulating strip is used therebetween to separate the electrode and the lid body. The lid body, a positive terminal, and the insulating strip are penetrated through rivets, so as to fix the positive terminal on the lid tightly. Further, an insulating strip is disposed below the lid body to isolate the rivet and the lid body, the electrode is welded at a lower end of the rivet, and the positive terminal is connected to a positive pole (or a negative pole) of the battery in the metal tank.
The cylindrical-shaped battery completes an external discharge application through an electrical connection between a conductive handle integrally formed or formed through welding and a conductive terminal penetrating the lid body.
It should be noted that, the current lithium battery, electrode structures connecting an internal battery in a metal tank to the external of a lid body are designed by penetrating the lid body, and a rivet or bolt (conductive terminal) is used as an external electrode. Such a manner of penetrating a lid body and using rigid materials may have the following disadvantages.
1. In terms of the electrode structure in a manner of penetrating a lid body, although a hermetic effect of the position can be achieved through an isolating strip, after being used for a long time, an isolating strip generally using a rubber may generate a gap due to aging; at this time, a through hole is not in a hermetic state, and water vapor may enter the internal of the metal tank of the battery from the position, which reduces the lifespan of the battery.
2. In terms of an external electrode using rigid materials, when more than two lithium batteries are connected in series or in parallel through an electrically connecting element, if the electrically connecting element is also of a rigid material, the through hole of the electrode will be damaged and deformed due to a relative stress of the rigid material when the element is used in high vibration environments such as electric bicycles and electric wheelchairs, so that the through hole is not in a hermetic state, and water vapor may enter the internal of the metal tank of the battery from the position, which reduces the lifespan of the battery.
3. Sectional areas of the part penetrating the lid body (rivet or bolt (conductive terminal)) of the electrode structure and an external contact point are relative smaller; such a structure principle is like that a wide main road has a disproportional bridge at a certain section, and thus it tends to generate a traffic jam at an entrance of the bridge when more cars intend to pass through the bridge. Likewise, when a large amount of electrons intend to pass through the electrode, a thermal energy may occur due to impendence of the part penetrating the lid body; thus, the temperature may be increased during the charge, and the temperature-rise effect may further cause a vicious circle of increase of the impedance, which may endanger safety. Moreover, when a large amount of electric charges are driven by a voltage to pass through the electrode, resistance of the electrode is increased, and the charge and discharge efficiencies are naturally reduced.
4. The existing electrode structure in a penetrating manner and the penetrated lid body thereof need to be installed with elements for hermeticity such as an insulating strip, and the manufacture difficulty and costs thereof are quite high for achieving the hermetic standard.